WICEN Vic: Using the Yaesu SCU-17 Interface Unit with Winlink Express / VARA-HF

[PeterY]

Thanks John for the explanation.  Will put this to my human memory bank.
73
PeterY 

-----Original Message-----
From: wicenvic <wicenvic-bounces at vic.wicen.org.au> On Behalf Of John & Bronwyn
Sent: Saturday, 16 July 2022 5:16 PM
To: WICEN distn list <wicenvic at vic.wicen.org.au>
Subject: WICEN Vic: Using the Yaesu SCU-17 Interface Unit with Winlink Express / VARA-HF

This note applies mainly to those operators who wish to use an older radio with the Yaesu SCU-17 Interface Unit to run Winlink Express using VARA-HF.

Some brief explanations:

.  The SCU-17 connects to a computer via USB and provides a sound card for digital mode Tx and Rx audio, plus a RS-232 radio control port to set frequency, mode, etc, plus another RS-232 port for PTT or FSK keying.  The RS-232 control port may require a further adapter for use with your radio, to adapt to CAT, CI-V or whatever radio control system your radio uses.  The SCU-17  can be used with a wide variety of programs for "soundcard" digital modes.

.  Winlink Express / VARA-HF provides messaging, email and file transfer over HF radio and is one of the two preferred WICEN digital systems for HF.  The other is EmcomWin and Pactor.

.  VARA-HF is a good "soundcard" data mode which plugs into the Winlink Express software.  Although not quite as robust as Pactor, it is far less costly, and performs much better than earlier "soundcard" modes such as Winmor and ARDOP.

The problem is, that Winlink Express / VARA-HF will not work with the
SCU-17 "PTT" RS-232 port.  When it attempts to open the port, it returns an error message that "the port may be in use by another program".   It isn't.  The problem is due to an incompatibility between Winlink Express and the "PTT" RS-232 port in the  SCU-17.  The Winlink organisation is aware of the issue but other issues have higher priority for attention.

With most newer radios, the "PTT" port in the SCU-17 is not required because Rx/Tx switching is actually controlled using the radio control port (CAT, CI-V, or similar).

For older radios which require PTT, there are two possible workarounds. The first is to use the VOX function in the radio, provided this will operate from the radio's DATA port.  However some radios use the PTT via the DATA port to switch the TX audio from the microphone to the data input.  VOX won't work with these radios.

The other workaround is to use a separate RS-232 port for the PTT control, via a USB / RS-232 dongle and an optocoupler for isolation, and just ignore the second RS-232 port in the SCU-17. This is a bit inconvenient but works well.

I hope this helps anyone who wants to use the SCU-17.  Apart from the issue outlined above, which only applies to Winlink Express / VARA-HF, it works very well.


Cheers,   John VK3ZRX



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